在 onCreate 中启动的 Intent 被多次调用

Question

我正在制作一个使用相机的应用程序，我希望在应用程序打开后立即打开默认相机。我目前在主要活动的 onCreate 方法中开始我的图像捕获意图。有时这工作得很好，但有时相机意图会连续启动 3 次。

public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        mImageView = (ImageView) findViewById(R.id.imageView1);
        mImageBitmap = null;

        Button picBtn = (Button) findViewById(R.id.pictureButton);
        setBtnListenerOrDisable(
                picBtn,
                mTakePicOnClickListener,
                MediaStore.ACTION_IMAGE_CAPTURE
        );

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.FROYO) {
            mAlbumStorageDirFactory = new FroyoAlbumDirFactory();
        } else {
            mAlbumStorageDirFactory = new BaseAlbumDirFactory();
        }
        dispatchTakePictureIntent(ACTION_TAKE_PHOTO_B);
    }

private void dispatchTakePictureIntent(int actionCode) {

        Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
        File f;
        try {
            f = setUpPhotoFile();
            mCurrentPhotoPath = f.getAbsolutePath();
            takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(f));
        } catch (IOException e) {
            e.printStackTrace();
            mCurrentPhotoPath = null;
        }

        startActivityForResult(takePictureIntent, actionCode);
    }

 protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (resultCode == RESULT_OK) {
            handleBigCameraPhoto();
        }
    }

private void handleBigCameraPhoto() {

        if (mCurrentPhotoPath != null) {
            setPic();
            galleryAddPic();
            lastPhotoPath = mCurrentPhotoPath;
            mCurrentPhotoPath = null;
        }

    }

 private void setPic() {

        /* There isn't enough memory to open up more than a couple camera photos */
        /* So pre-scale the target bitmap into which the file is decoded */

        /* Get the size of the ImageView */
        int targetW = mImageView.getWidth();
        int targetH = mImageView.getHeight();

        /* Get the size of the image */
        BitmapFactory.Options bmOptions = new BitmapFactory.Options();
        bmOptions.inJustDecodeBounds = true;
        BitmapFactory.decodeFile(mCurrentPhotoPath, bmOptions);
        int photoW = bmOptions.outWidth;
        int photoH = bmOptions.outHeight;

        /* Figure out which way needs to be reduced less */
        int scaleFactor = 1;
        if ((targetW > 0) || (targetH > 0)) {
            scaleFactor = Math.min(photoW / targetW, photoH / targetH);
        }

        /* Set bitmap options to scale the image decode target */
        bmOptions.inJustDecodeBounds = false;
        bmOptions.inSampleSize = scaleFactor;
        bmOptions.inPurgeable = true;

        /* Decode the JPEG file into a Bitmap */
        Bitmap bitmap = BitmapFactory.decodeFile(mCurrentPhotoPath, bmOptions);

        /* Associate the Bitmap to the ImageView */
        mImageView.setImageBitmap(bitmap);
        mImageView.setVisibility(View.VISIBLE);
    }

Answer 1

我认为 Nathaniel 给了你很好的建议，将你的相机意图转移到 onResume 中。

但是，您需要区分 onResume 是您的第一次开始的活动，以及由于您的活动在相机意图完成后恢复而正在发生的活动。如果你不这样做，你会得到你看到的循环。

为此，您可以更改您的onActivityResult() 以在您的活动中设置一个名为isResumingFromCaptureIntent 的成员变量。当 resultCode 与您用于启动相机意图的内容匹配时，在 onActivityResult 中将其设置为 true。然后，在您的 onResume 中，检查 isResumingFromCaptureIntent，如果为 true，您知道您不需要启动相机意图并且可以设置为 false 并继续您的活动需要执行的任何其他操作。

Answer 2

看这里：

Android: onCreate() getting called multiple times (and not by me)

我可以提供的一条指导是尝试将调用转移到

public void onResume(){

}

您将获得所需的自动进入相机的行为，但这可能会减少一些额外的调用，因为它仅在实际向用户显示活动时发生（包括从其他应用程序返回等） ..)。

Answer 3

在 onCreate 方法中，我添加了检查是否之前调用过 onCreate 的逻辑。我通过检查传入的捆绑包是否为空来做到这一点

public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        mImageView = (ImageView) findViewById(R.id.imageView1);
        mImageBitmap = null;

        Button picBtn = (Button) findViewById(R.id.pictureButton);
        setBtnListenerOrDisable(
                picBtn,
                mTakePicOnClickListener,
                MediaStore.ACTION_IMAGE_CAPTURE
        );

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.FROYO) {
            mAlbumStorageDirFactory = new FroyoAlbumDirFactory();
        } else {
            mAlbumStorageDirFactory = new BaseAlbumDirFactory();
        }

        if(savedInstanceState == null)
            dispatchTakePictureIntent(ACTION_TAKE_PHOTO_B);
    }